The present invention relates to a method of forming micro patterns of a semiconductor device and, more particularly, to a method of forming micro patterns of a semiconductor device, in which more micro patterns than allowed by a resolution limit of an exposure apparatus can be formed.
In general, the degree of integration of semiconductor devices is concerned with the resolution limit of an exposure apparatus used to fabricate the semiconductor devices. In order to enhance the degree of integration of semiconductor devices, an exposure apparatus with excellent resolution is required. However, as the degree of integration becomes smaller than 40 nm, an exposure apparatus with an excellent resolution is required, which results in increased manufacturing costs.
Research has been conducted to form more micro patterns than the resolution limit of an exposure apparatus allows by changing the manufacturing process. For example, a method has been proposed of forming first photoresist patterns having a pitch, which is twice the pitch of target patterns, and forming second photoresist patterns having the same pitch as that of the first photoresist patterns between the first photoresist patterns. However, if misalignment occurs in an exposure process of forming the second photoresist pattern, a distance between the first photoresist pattern and the second photoresist pattern cannot be maintained uniformly. The likelihood of misalignment increases as the degree of integration increases, which increases the failure rate.